Motor driven compressors for refrigerating machines



y 1970 TUNEO MONDEN ETAL 3,514,225

MOTOR DRIVEN COMPRESSORS FOR REFRIGERATING MACHINES Filed June 19. 1968F I G.

EVAPORATOR INVENTOR5 United States Patent 3,514,225 MOTOR DRIVENCOMPRESSORS FOR REFRIGERATIN G MACHINES Tuneo Monden, Tokyo, and MakotoWatanabe, Kawasakishi, Japan, assignors to Tokyo Shibaura Electric Co.,Ltd., Kawasaki-shi, Japan, a corporation of Japan Filed June 19, 1968,Ser. No. 738,189 Claims priority, application Japan, June 21, 1967, 42/39,811 Int. Cl. F04c 29/02 US. Cl. 230--207 2 Claims ABSTRACT OF THEDISCLOSURE In a motor driven compressor for a refrigerator comprising ahermetically sealed casing containing the motor compressor and lubricanta suction cup is connected in series with a suction pipe and ismaintained in heat exchange relationship with the lubricant.

BACKGROUND OF THE INVENTION This invention relates to a motor drivencompressor for a refrigerating machine and more particularly to a motordriven rotary compressor contained in a hermetically sealed casingespecially suitable for use in room air conditioners and the like.

In a refrigerating system comprising a motor driven compressor, acondenser and an evaporator the gaseous refrigerant compressed by thecompressor is liquidified in the condenser and the liquid refrigerant isthen supplied to the evaporator through a capillary tube to beevaporated therein. The gaseous refrigerant in the evaporator is suckedinto a cylinder of the compressor through a suction pipe.

In such a refrigerating system, liquid refrigerant in the evaporator maynot completely evaporate when the room air conditioner is restartedafter a long period of idleness, or the evaporator is excessivelycooled, or the quantity of refrigerant sealed in is excessive. In such acase there is a tendency that the liquid refrigerant is entrained in thegaseous refrigerant sucked into the compressor so that so-called liquidcompression occurs. As a result, there occur many difficulties such asdamage to the discharge valve or other portions of the compressor andseizure of the driving shaft due to excessive compression force. This isespecially dangerous in the so-called high pressure type compressor inwhich the interior of the sealed casing of the motor compressor ismaintained at a high pressure because the volume between the suctionpipe and the compressor cylinder is extremely small. Further,compression of the gaseous refrigerant in the compressor createsfluctuation in the pressure of the compressed gas in the sealed casing,thus causing noise.

SUMMARY OF THE INVENTION In accordance with this invention, a suctioncup having a predetermined volume or space is connected in a suctionpassage of the gaseous refrigerant to the compressor in such a positionthat the cup is at least partially immersed in the lubricating oilcontained in the bottom of the sealed casing so as to vaporize orseparate the liquid refrigerant thus preventing liquid compression anddamage of the discharge valve and other portions of the compressor.

As the suction cup has a predetermined volume it can reduce the pressurepulsation caused by the compression of gaseous refrigerant in thecylinder, thus acting as an intake muflier to eliminate noise. It isadvantageous to cause the lubricating oil which has completed itslubricating function and is returning from the upper chamber 3,514,225Patented May 26, I970 "ice to the lower chamber in the sealed casing todrop on the suction cup to effectively cool the lubricant.

BRIEF DESCRIPTION OF THE DRAWING Further object and advantages of theinvention can be more fully understood from the following descriptiontaken in connection with the accompanying drawing in which:

FIG. 1 shows an elevational view, partly in section, of a motor drivenrotary compressor provided with a suct on cup connected in series with asuction pipe; and

FIG. 2 shows a cross-section taken along a line II-II in FIG. 1 andviewed in the direction of arrows.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to theaccompanying drawing illustrating a preferred embodiment of thisinvention, a rotary compressor shown in FIG. 1 comprises a hermeticallysealed casing 1 consisting of interfitted upper and lower casing halves2 and 3, an electric motor 4, a frame 5 also acting as a bearing and acompressor 6 contained in the casing. A stator core 8 having a statorcoil 7 of the electric motor 4 is secured to the iner wall of the uppercasing half as by force fit. The rotor rotating in the stator core 8with an air gap 9 therebetween is provided with axial air ducts 11 andspiral oil grooves 13a and 13b are formed on the lower portion of amotor shaft 12. The frame 5 comprises an annular fitting member 15, ahorizontal partition 14 and a central bearing member 17 adapted tojournal the motor shaft 12 and a flange .16. The fitting member 15 isforce fit in the lower portion of the upper casing half 2 beneath thestator core 8, while the flange 16 is fit in the overlapped portion 18of upper and lower casing halves 2 and 3. The horizontal partition 14 isprovided with a perforation 19 intercommunicating the upper chambercontaining the motor and the lower chamber containing a compressor 6 anda perforation 20 adapted to interconnect the interior of the uppercasing half 2 and a muffler chamber of the compressor to be describedlater. The compressor comprises a cylindrical rotor 22 fit around aneccentric 21 formed on the lower end of the motor shaft 12 and a hollowcylinder 23 which is securely fixed to the horizontal partition 14 ofthe frame 5 by means of bolts 25 together with an end plate 24. As shownin FIG. 2 of the cylinder 23 is formed with a cylindrical chamber 26containing the eccentric 21 of the shaft .12 and rotor 22. Chamber 26 isdivided into a low pressure gas chamber 26a and a high pressure gaschamber 26b by means of a slidable blade or vane 30 which is normallyurged against the inner periphery of the cylinder by a compressionspring 29. A muffler chamber 31 is formed in the cylinder which iscommunicated with the perforation 20 extending through the horizontalpartition 14 and with the high pressure gas chamber 26b through adischarge port 32 which is normally closed by a discharge valve 33, themovement thereof being limited by a stop 34. A body of lubricating oil35 is contained in the bottom of the lower casing half 5.

One of the features of this invention lies in the provision of a suctioncup 36 having a predetermined volume and connected between suction pipes27a and 27b which convey gaseous refrigerant to a suction port 28 of thecylinder 23. As shown in the drawing, the suction cup 36 is disposed ina space between cylinder 23 and lower casing half 3 to partially dip inlubricant 35. As shown in FIG. 1, the suction pipe 27a is connected tothe lower portion of the suction cup 36 whereas the suction pipe 27b isconnected to the upper portion. Further, the suction cup 36 is disposedimmediately beneath the perforation 19 extending through the horizontalpartition 14.

The compressor of this invention operates as follows: Upon energizationof electric motor 4 the eccentric 21 of its shaft 12 rotateseccentrically about the axis thereof. As a result, the rotor 22 iscaused to roll along the inner surface of the cylinder so that thegaseous refrigerant is sucked into the low pressure gas chamber 26a andthe gaseous refrigerant in the high pressure gas chamber is compressedto a high pressure until finally discharged into the mufller chamber 31through discharge valve 33. The high pressure gas is then dischargedinto the upper casing half 2 and supplied to a condenser through adischarge pipe 37.

The lubricating oil 35 contained in the bottom of the lower casing half3 serves to lubricate movable parts and to provide gastight seal betweenhigh and low pressure sides. More particularly, the oil pumped up by therotation of motor shaft 12 is fed to spiral oil grooves 13a and 13bthrough an oil duct 38 extending through shaft 12. The oil supplied togroove 13b is supplied under pressure to the interior of the cylinder23, especially into the low pressure gas chamber 26a, but major portionof the pumped up oil is supplied to the bearing member 17 through theoil groove 13a, then flows down on the partition wall 14 and finallyreturns to the bottom of the lower casing half 3 through perforation 19.

The oil supplied into the cylinder 23 via spiral oil groove 13b forms oilseals in a gap of several tens microns between the rotor 22 and theinner surface of the cylinder and in gaps between the end surfaces ofthe rotor 22 and the lower surface of partition 14 and the upper surfaceof end plate 24. Since the oil utilized to form these oil seals is underhigh pressure it is supplied to the low pressure gas chamber 26a througha slot slidably receiving the blade 30 and through end gaps of therotor.

Another feature of this invention lies in the provision of the suctioncup 36 having a predetermined volume at an intermediate point of thesuction pipe to be immersed in the lubricating oil 35. This suction cupserves to vaporize or separate liquid refrigerant entrained in thegaseous refrigerant supplied to the compressor through the suction pipethereby relieving the compressor from overload while at the same timeeffectively cools the lubricating oil thus improving lubrication andcooling of the driving motor. Thus the lubricating oil contained in thebottom of the sealed casing is normally maintained at a temperature offrom 50 C. to 80 C. so that liquid refrigerant which might be entrainedin the gaseous refrigerant from the evaporator operating at atemperature of from C. to 10 C. is vaporized when the compressor isrestarted after a long period of idleness, the temperature of thelubricating oil is not sufficiently high. Under this condition, however,as the suction pipe 27b communicated with the compressor is opened inthe upper portion of the suction cup 36 the liquid refrigerant would notbe introduced directly into the compressor because it is collected inthe bottom of the suction cup.

Further, according to this invention the lubricating oil whosetemperature has been increased while passing through bearing or movingparts or by contacting with heated portions of the motor can beeffectively cooled by the suction cup 35 because heated oil is poured onthe suction cup 36 through perforation 19.

Additionally, the suction cup having a considerably large volume acts asan intake mufiler to alienate fluctu- 4 ation in the pressure of thecompressed gas thus reducing the noise.

From the foregoing description it will be clear that according to thisinvention there is provided an improved motor compressor by which liquidrefrigerant can be evaporated or separated from the gaseous refrigerant,the lubricant oil is effectively cooled to increase the lubrica-r tionof moving parts as well as the cooling of driving motor and the noise ofthe compressor can be reduced by providing a suction cup of apredetermined volume in the suction pipe of the compressor and in heatexchange relationship with the lubricating oil.

In accordance with the provisions of the patent statutes, we haveexplained the principle and operation of our invention and haveillustrated and described what We consider to represent the bestembodiment thereof. However, we desire to have it understood that withinthe scope of the appended claims, the invention may be practicedotherwise than as specifically illustrated and described.

' What is claimed is:

1. In a motor driven rotary compressor unit comprising a verticallydisposed hermetically sealed cylindrical casing (1). having mountedtherein a suction pipe (27a, 27b) for circulating a refrigerant to theexterior and back to the casing, said casing containing a motor (4)towards the upper cylindrical side and a compressor (6) towards thelower cylindrical side connected to the motor by means of a frame (5)separating said motor (4) and said compressor (6), said frame (5) havinga bearing member (17) journalling a motor shaft ('12) and wherein alubricating oil (35) storage zone is located in the bottom of saidsealed casing (1), and lubricating oil circulating means (13a, 13b) areprovided along said shaft (12) for carrying lubricating oil from saidstorage zone towards said upper cylindrical side with a perforation (19)in said frame (5) for returning said oil to said storage zone; theimprovement therein wherein a suction cup (36) having a relatively largevolume is serially inserted in said suction pipe (27a, 2711), saidsuction cup being least partiallyimmersed in said lubricating oil (35)storage zone and said suction cup (36) being arranged in a positionopposite to and under said perforation (19) in said frame (5), wherebyhot oil returning to said storage zone from said upper cylindrical sideis cooled 'by the refrigerant in said suction cup (36) while anyregrigerant in the liquid phase in said suction cup is heated by hot oilto the vapor phase.

2. A rotary compressor. according to claim 1 said suction cup having anupper and a lower section, said compressor (6) including a suction partconnected to said suction cup upper section, and, said compressor unithaving an external evaporator serially connected to said suction cuplower section.

References Cited UNITED STATES PATENTS 2,096,052 lO/1937 McMahon.3,066,857 12/1962 McCloy 2 30232 3,311,292 3/ 1967 Conner 23 0-207ROBERT -M. WALKER, Primary Examiner US. Cl. X.R. 417-410, 902

